Rockwell hardness : The test of cylinder tube on Rockwell hardness is actually the same as the Brinell hardness test. Both use the indentation test method, but the difference is that Rockwell mainly conducts the indentation depth Among them, the Rockwell hardness test method is widely used, because Rockwell hardness is more suitable for testing soft metal materials, which effectively compensates for the lack of Brinell hardness test, and the method and method are relatively simple. But because the indentation is relatively small, the hardness value is not as accurate as the Brinell method. Brinell hardness : In the standard test of the entire cylinder tube, the Brinell hardness is widely used, and its indentation is often used to indicate the main hardness of the material, which is not only relatively intuitive but also very convenient. However, if it is a harder or thinner steel, the method is less suitable. Vickers hardness : This hardness test is still an indentation test method. It is more suitable for thinner metals or materials with higher surface hardness. It has the dual advantages of Rockwell and Brinell. The shortcomings of hardness testing are overcome, but it is not as simple and convenient as Rockwell. Therefore, Vickers is rarely used when steel pipe standards are high.